With reciprocating piston internal combustion engines, an oil-containing leakage gas, so-called blow-by gas, is produced in the crankcase. The return thereof into the combustion process is legally mandated worldwide, and takes place in so-called closed crankcase ventilation systems. The most important tasks of a crankcase ventilation system are oil separation and oil return into the crankcase, as well as the regulation of the crankcase pressure. The requirements for oil separation have been steadily increasing in recent years, as legislation on emissions has grown increasingly stringent, in order to protect emissions-related engine components such as exhaust gas turbochargers, intercoolers, or sensors from performance loss due to oil contamination. Thus, oil separation is important not only in minimizing oil consumption, but also in making what is now an essential contribution to compliance with emissions legislation throughout the lifetime of the vehicle. In addition to oil separation, a crankcase ventilation system contains other important components, such as, for example, a pressure control valve, depending on the ventilation design.
A pressure control valve for a crankcase ventilation system of an internal combustion engine is disclosed, for example, in documents DE 10 201 3 005 624 A1, WO 2005 088 417 A1 and WO 2007 13 50 82 A2. Generally-known pressure control valves have a valve closing body that operates in conjunction with a valve seat, and a return spring that acts on the valve closing body in the direction facing away from the valve seat (DE 10 2004 02 22 75 A1).
In order to extend the life of the return spring in a pressure control valve for an internal combustion engine, DE 10 2004 02 22 75 A1 proposes arranging the return spring on the side of the valve closing body facing away from the valve seat, and thus preventing the return spring from contacting aggressive blow-by gases emerging from the crankcase. Documents WO 2007 13 50 82 A2 and JP 2003 33 65 16 A disclose arranging the return spring on the atmosphere side of a pressure control valve.
WO 2005 08 84 17 A1, WO 2009 15 63 03 A1, DE 10 2004 02 22 75 A1, and EP 1 32 95 98 A1 disclose fastening a membrane configured as a sealing element onto a valve element by means of at least one spraying process, in particular, by injection-molding onto a valve element or overmolding a valve element.
With known pressure control valves, the valve seat of the pressure control valve is arranged on the outside of a side wall of the crankcase ventilation system (DE 10 2013 005 624 A1) or formed by a side wall of the housing of the crankcase ventilation system (WO 2005/088 417 A1).
The invention addresses the problem of developing a filter element of the aforementioned type, an oil separator of the aforementioned type, and a method of the aforementioned type, in such a manner that the functions thereof are optimized, in particular, that the crankcase ventilation system takes up the least installation space possible.